Quantum Heat Engine With Identical Particles And Level Degeneracy

In this thesis,we study the effects of identical particles with level degeneracy on the performance of quantum Otto heat engine and Stirling heat engine.In chapter 1,after briefly describing the main achievement of the thermodynamics and quantum mechanics,we give an introduction about the recent progress on the quantum thermodynamics and quantum heat engine.In chapter 2,the background knowledge,including the 4 basic quantum thermodynamics processes,the classical Otto heat engine and Stirling heat engine and the identical particles in quantum mechanics,is presented.In chapter 3,the partition functions of the identical particles with level degeneracy are calculated.Here we consider two-fold and three-fold degeneracy in ground state and excited state respectively.We give the detailed calculations by virtue of the particle-number representation for the case of identical particles with two-fold degeneracy in excited state,and other results are shown in the appendix.In chapter 4,we consider the effects of identical particles with level degeneracy on the performance of quantum Otto heat engine.The work outputs as a function of the parameter(?) under different condition are plotted.Our results show that the degeneracy in ground state improves the work output.For multi-particle case,we find the work output depends on the temperature obviously for Bosons.While the work decreases for Fermion,in most cases.One exception is that for the degeneracy in ground state,the work increases in the low temperature limitation for Fermions.In chapter 5,we study the quantum Stirling heat engine in a similar manner.In order to improve the efficiency,the regenerator is used in two isochoric process,which is same to the classical case,Here we are consider the work output and the efficiency,we find the results for the work output is same to the Otto heat engine case.However,the efficiency is quite different.In the quantum Stirling heat engine with optional regeneration the maximum efficiency decrease for Bosons.For Fermions the maximum efficiency decreases when the degeneracy is in excited state while it increases when the degeneracy is in the ground state.The discussions and conclusions are presented at the end of the thesis.